Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nature's toughest substances decoded

05.12.2017

Rice University engineers develop computer maps to help design shell-like platelet-matrix composites

How a material breaks may be the most important property to consider when designing layered composites that mimic those found in nature. A method by Rice University engineers decodes the interactions between materials and the structures they form and can help maximize their strength, toughness, stiffness and fracture strain.


An illustration shows a model platelet-matrix composite in the foreground and nacre, one of nature's toughest materials, in the background. Rice University researchers have developed computer simulations to decode natural materials to guide research into synthetic multifunctional composites.

Credit: Multiscale Materials Laboratory/Rice University

Usage Restrictions: For news reporting purposes only

In a study that required more than 400 computer simulations of platelet-matrix composite materials like mother-of-pearl, Rice materials scientist Rouzbeh Shahsavari and visiting scholar Shafee Farzanian developed a design map to help with the synthesis of staggered composites for applications at any scale, from microelectronics to cars to spacecraft, where lightweight, multifunctional structural composites are key.

The model integrates the geometries and properties of various platelet and matrix components to compute the composite's strength, toughness, stiffness and fracture strain. Changing any architectural or compositional parameter adjusts the entire model as the user seeks the optimal psi, a quantification of its ability to avoid catastrophic failure.

The research appears in the Journal of Mechanics and Physics of Solids.

Natural composites are common. Examples include nacre (mother-of-pearl), tooth enamel, bamboo and the dactyl clubs of mantis shrimp, all of which are nanoscale arrangements of hard platelets connected by soft matrix materials and arranged in overlapping brick-and-mortar, bouligand or other architectures.

They work because the hard parts are strong enough to take a beating and flexible enough (due to the soft matrix) to distribute stress throughout the material. When they fracture, they're often able to distribute or limit the damage without failing entirely.

"Lightweight natural materials are abundant," Shahsavari said. "In these types of materials, two kinds of toughening happen. One comes before crack propagation, when the platelets slide against each other to relieve stress. The other is part of the beauty of these materials: the way they toughen after crack propagation.

"Even when there is a crack, it does not mean a failure," he said. "The crack may be arrested or deflected several times between the layers. Instead of going straight through the material to the surface, which is a catastrophic failure, the crack bumps into another layer and zigzags or forms another complex pattern that delays or entirely prevents the failure. This is because a long and complex crack trajectory requires much more energy to drive it, compared with a straight crack."

Scientists and engineers have worked for years to replicate the light, tough, strong and stiff properties of natural materials, either with hard and soft components or combinations of different platelet types.

To engineers, stiffness, toughness and strength are distinct characteristics. Strength is the ability of a material to stay together when stretched or compressed. Stiffness is how well a material resists deformation. Toughness is the ability of a material to absorb energy before failure. In a previous paper, the Rice lab created maps to predict the properties of composites based on those parameters before crack propagation.

The addition of crack-induced toughening in natural and biomimetic materials, Shahsavari said, is another potent and interesting source of toughening that provides extra lines of defense against failure. "The models uncovered nonintuitive synergies between the before- and after-crack toughening phenomena," he said. "They showed us what architectures and components would allow us to combine the best properties of each."

The baseline model allowed the researchers to adjust four values for each simulation: characteristic platelet length, plasticity of the matrix, the platelet dissimilarity ratio (when more than one type of platelet is involved) and the platelet overlap offset, all of which are important to the composite's properties.

Over the course of 400 simulations, the model revealed the greatest factor in psi may be platelet length, Shahsavari said. It showed that short platelets largely yield fracture control to the plasticity of the soft matrix, while long platelets take it back. Platelet lengths that distribute the fracture evenly and allow maximum crack growth can achieve the optimal psi and make material better able to avoid catastrophic failure.

The model will also help researchers design whether a material will fail with a sudden fracture, like ceramics, or slowly, like ductile metals, by switching components, using contrasting platelets or changing the architecture.

Shahsavari is an assistant professor of civil and environmental engineering and of materials science and nanoengineering.

###

The National Science Foundation and Rice's Department of Civil and Environmental Engineering supported the research. Supercomputing resources were supplied by the National Institutes of Health and an IBM Shared University Research Award in partnership with Cisco, Qlogic and Adaptive Computing, as well as Rice's National Science Foundation-supported DAVinCI supercomputer administered by the Center for Research Computing and procured in partnership with Rice's Ken Kennedy Institute for Information Technology.

Read the abstract at http://www.sciencedirect.com/science/article/pii/S0022509617307937

This news release can be found online at http://news.rice.edu/2017/12/04/natures-toughest-substances-decoded/

Follow Rice News and Media Relations via Twitter @RiceUNews

Related materials:

Maps predict strength of structures: http://news.rice.edu/2015/03/16/maps-predict-strength-of-structures-2/

Multiscale Materials Laboratory home page: http://rouzbeh.rice.edu/

George R. Brown School of Engineering: http://engineering.rice.edu

Rice Department of Civil and Environmental Engineering: http://www.ceve.rice.edu

Rice Department of Materials Science and NanoEngineering: https://msne.rice.edu

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for quality of life and for lots of race/class interaction and No. 2 for happiest students by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview.

Media Contact

David Ruth
david@rice.edu
713-348-6327

 @RiceUNews

http://news.rice.edu 

David Ruth | EurekAlert!

Further reports about: catastrophic failure crack propagation failure fracture platelet stiffness

More articles from Materials Sciences:

nachricht Looking at linkers helps to join the dots
10.07.2020 | King Abdullah University of Science & Technology (KAUST)

nachricht Goodbye Absorbers: High-Precision Laser Welding of Plastics
10.07.2020 | Fraunhofer-Institut für Lasertechnik ILT

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron cryo-microscopy: Using inexpensive technology to produce high-resolution images

Biochemists at Martin Luther University Halle-Wittenberg (MLU) have used a standard electron cryo-microscope to achieve surprisingly good images that are on par with those taken by far more sophisticated equipment. They have succeeded in determining the structure of ferritin almost at the atomic level. Their results were published in the journal "PLOS ONE".

Electron cryo-microscopy has become increasingly important in recent years, especially in shedding light on protein structures. The developers of the new...

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

Black phosphorus-based van der Waals heterostructures for mid-infrared light-emission applications

13.07.2020 | Physics and Astronomy

Polarization of Br2 molecule in vanadium oxide cluster cavity and new alkane bromination

13.07.2020 | Life Sciences

Researchers present concept for a new technique to study superheavy elements

13.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>